WASHINGTON — Secretary of State John Kerry on Thursday called on the U.N. General Assembly to move swiftly to approve a U.S.-Russia deal to eliminate Syria’s chemical weapons, saying there is no time to argue with those who remain unconvinced that the Syrian regime carried out a chemical attack last month that killed hundreds.

Kerry didn’t mention Russian President Vladimir Putin, but his remarks were a clear attempt to rebut Putin’s statement that Russia has strong grounds to believe that Syrian rebels — not President Bashar Assad’s regime — were responsible for the Aug. 21 attack.

Speaking at a conference, Putin said, “We have every reason to believe that it was a provocation, a sly and ingenious one.” He said those who perpetrated the attack relied on “primitive” technology, using old Soviet-made ammunition no longer in the Syrian army’s inventory.

While the U.N. report did not ascribe blame, the U.S., Britain, France and others believe that the report’s findings offer conclusive evidence that the attack was conducted by the Syrian military. Assad, in an interview this week with Fox News Channel, denied that his regime was responsible for the attack.

The U.S., Britain and France pointed to evidence in the report — especially the type of rockets, the composition of the sarin agent and trajectory of the missiles — to declare that Assad’s government was responsible. Moreover, they argue that there is no evidence that opposition forces possess sarin gas.

“So there you have it. Sarin was used. Sarin killed,” Kerry said. “The world can decide whether it was used by the regime, which has used chemical weapons before — the regime which had the rockets and the weapons — or whether the opposition secretly went unnoticed into territory they don’t control to fire rockets they don’t have, containing sarin that they don’t possess to kill their own people.

“And then, without even being noticed, they just disassembled it all and packed up and got out of the center of Damascus controlled by Assad. Please. This isn’t complicated.”

The U.S. wants a new U.N. resolution now under discussion to make the U.S.-Russia agreement reached last week in Geneva legally binding in a way that is verifiable and enforceable. The U.S. and Russia are arguing over putting the resolution under Chapter 7 of the U.N. Charter. Chapter 7 deals with threats to international peace and security and has provisions for enforcement by military or nonmilitary means, such as sanctions.

“We really don’t have time today to pretend that anyone can have their own set of facts approaching the issue of chemical weapons in Syria,” Kerry said. “This fight about Syria’s chemical weapons is not a game. It’s real. It’s important. It’s important to the lives of people in Syria, it’s important to the region, it’s important to the world that this be enforced — this agreement that we came out of Geneva with.”